Divergent effects of switching from cytology to HPV-based screening in the Nordic countries

BACKGROUND

Cervical cytology has been the primary method of cervical cancer screening for decades. Tests that detect viral HPV are shown in several randomized trials to provide better protection against cancer compared with cytology. HPV-based screening has been implemented alongside cytology in the Nordic countries for several years. The aim of this study was to compare cytology and HPV-based screening in the colposcopy referrals and detection rates of cervical lesions.

METHODS

Individual-level screening data from Finland, Iceland, Norway and Sweden were harmonized and aggregated locally. We utilized data for tests taken during years 2015-17 and biopsies taken during years 2015-19 to allow 24 months of follow-up. Age-standardized estimates and age-adjusted risk ratios for six different outcomes of screening management were calculated.

RESULTS

The age-standardized colposcopy rates were higher in HPV-based testing compared with cytology in Finland (3.5% vs. 0.9%) and Norway (6.0% vs. 4.1%) but lower in Sweden (3.7% vs. 4.9%). The relative detection rate of cervical intraepithelial neoplasia grade 2 and above in HPV-based testing compared with cytology was highest in Finland (RR 2.37, 95% CI 2.13-2.63) and Norway (RR 1.66, 95% CI 1.57-1.72) while in Sweden the difference was not statistically significant (RR 0.98, 95% CI 0.95-1.00).

CONCLUSIONS

The effects of implementing HPV screening varied by country as different screening algorithms were implemented. HPV-based screening increases colposcopy rates mainly through referrals from increased repeat testing and detection rate is therefore significantly higher compared with cytology. Monitoring of these indicators in subsequent rounds of HPV-based screening remains essential.

Cervical cancer mortality in Norway according to screening attendance and age

INTRODUCTION

The association between cervical cancer screening and reduction of cervical cancer has been dealt with in much research. However, little has been published on the association between screening and cervical cancer mortality. We assessed cervical cancer deaths according to screening history, histopathology, and age among women in, under, and above screening age.

MATERIAL AND METHODS

In this nationwide, registry-based case-control study from Norway, we included 817 cervical cancer deaths in women diagnosed with cervical cancer in the period 1998-2009. We matched each case with 10 population-based controls free from cervical cancer, obtained by density-based sampling. Odds ratios (ORs) with 95% confidence intervals (CIs) for the association between screening attendance and cervical cancer mortality were estimated using conditional logistic regression models.

RESULTS

Of all fatal cervical cancers, 35% were diagnosed among women over screening age and altogether, 83% were either in age groups not covered by the screening program or in non-attenders of screening age. The estimated risk reduction associated with a cytology test in the preceding 3.5 years was 80% in screening age 25-69 years (OR 0.20; 95% CI 0.16-0.24) with the largest reduction in squamous cell carcinomas (84%) but also a substantial estimated risk reduction of 65% for adenocarcinomas. The associated risk reduction was strongest in women aged 45-69 years, with ORs in the range 0.09-0.18, compared with ORs 0.42-1.35 in women aged 25-39 years.

CONCLUSIONS

To reduce the mortality of cervical cancer, screening programs should focus on increasing adherence to the program, as half of all the fatal cases were in the non-attender group. Further assessments regarding the potential preventive impact of extending screening to women over the current screening age should be considered.

Setting the record straight-Correcting uterine cancer incidence and mortality in the Nordic countries by reallocation of unspecified cases

INTRODUCTION

The incidence of and mortality from cancers of the cervix uteri and corpus uteri are underestimated if the presence of uterine cancers, where the exact topography (site of origin) is not specified, is omitted. In this paper we present the corrected figures on mortality from and incidence of cervix and corpus uteri cancers in the Nordic countries by reallocating unspecified uterine cancer deaths and cases to originate either from the corpus uteri or cervix uteri. To further validate the accuracy of reallocation, we also analyzed how well the reallocation captures the changes occurring as the result of a transition in cause of death coding in Norway that took place in 2005.

MATERIAL AND METHODS

This study uses data available in the NORDCAN database, which contains aggregated cancer data from all the Nordic countries for the years 1960-2016. The unspecified uterine cancer cases and deaths were reallocated to either cervix uteri or corpus uteri based on the estimated probability that follows the distribution of cases and deaths with verified topography. The estimated proportions of cases and deaths for both cancers were calculated for each combination of age group, year, and country as a proportion of cases (and deaths, respectively) with known topography. Annual age-standardized rates were calculated by direct age-adjustment.

RESULTS

The proportions of unspecified uterine cancers were higher in the mortality data than in incidence data, with mean values for 1960-2016 ranging between 5.1% and 26.6% and between 0.2% and 6.8% by country, respectively. In the Nordic countries combined, the reallocation increased the number of cases by 4% and deaths by approximately 20% for both cancers. Finland was the only Nordic country where the mortality rate did not increase substantially after reallocation.

CONCLUSIONS

The reallocation procedure had a significant impact on mortality from cancers of the cervix and corpus uteri for countries where the proportion of cancer deaths coded as uterus, not otherwise specified, is substantial. More effort to validate cause of death data with incidence data from cancer registries is warranted to avoid erroneous conclusions of temporal trends based on uncorrected cancer burden.

Cervical cancer in women under 30 years of age in Norway: a population-based cohort study

BACKGROUND

We compared women with incident cervical cancer under the age of 30 with older women with regard to stage, morphology, screening history and cervical cancer mortality in a population-based cohort study.

METHODS

We included data from the Cancer Registry of Norway. Incidence rates (per 100,000 women-years) were calculated and joinpoint regression was used to analyse trends. The Nelson-Aalen cumulative hazard function for risk of cervical cancer death during a 15-year follow-up was displayed. The hazard ratios (HRs) of cervical cancer mortality with 95% confidence intervals (CIs) were derived from Cox regression models.

RESULTS

The incidence of cervical cancer in women under the age of 30 has almost tripled since the 1950s, with the steepest increase during 1955-80 (with an annual percentage change (APC) of 7.1% (95%CI 4.4-9.8)) and also an increase after 2004 (3.8% (95%CI -1.3-9.2)). Out of 21,160 women with cervical cancer (1953-2013), 5.3% were younger than 30 years. A lower proportion of younger women were diagnosed at more advanced stages and a slightly higher proportion were diagnosed with adenocarcinoma and adenosquamous carcinoma comparing women above 30 years. The cumulative risk of cervical cancer death was lower for patients under the age of 30. However, the difference between the age groups decreased over time. The overall adjusted HR of cervical cancer mortality was 0.69 (95% CI 0.58-0.82) in women diagnosed under the age of 30 compared to older women.

CONCLUSION

There has been an increase in cervical cancer incidence in women under the age of 30. Cervical cancer in younger women was not more advanced at diagnosis compared to older women, and the cervical cancer mortality was lower.

Comparison of cytology and human papillomavirus-based primary testing in cervical screening programs in the Nordic countries

OBJECTIVE

To compare primary test positivity in cytology and human papillomavirus-based screening between different Nordic cervical cancer screening programs using harmonized register data.

METHODS

This study utilized individual-level data available in national databases in Finland, Iceland, Norway, and Sweden. Cervical test data from each country were converted to standard format and aggregated by calculating the number of test episodes for every test result for each calendar year and one-year age group and test method. Test positivity was estimated as the proportion of positive test results of all primary test episodes with a valid test result for "any positive" and "clearly positive" results.

RESULTS

The age-adjusted rate ratio for any positive test results in primary human papillomavirus-based screening compared to cytology was 1.66 (95% CI 1.64-1.68). The age-adjusted rate ratio for clearly positive test results was 1.02 (95% CI 1.00-1.05). A decreasing rate ratio by age was seen in both any positive and clearly positive test results. Test positivity increased over time in Iceland, Norway, and Sweden but slightly decreased in Finland.

CONCLUSIONS

The probability of any positive test result was higher in human papillomavirus testing than in primary cytology, even though the cross-sectional detection of a clearly positive test result was the same. Human papillomavirus testing can still lead to an improved longitudinal sensitivity through a larger number of follow-up tests and the opportunity to identify women with a persistent human papillomavirus infection. Further research on histologically verified precancerous lesions is needed in primary as well as repeat testing.

Adherence to international recommendations in the governance and organisation of Nordic cervical cancer screening programmes

INTRODUCTION

Screening has been the primary reason for the decline in the incidence and mortality of cervical cancer in the Nordic countries since the beginning of screening in the 1960s. Recently, the incidence of cervical cancer has increased in the Nordic countries indicating the need to look closely at possibilities for further improvement in screening. This article provides an overview of cervical cancer screening programmes in the Nordic countries and whether the programmes adhere to international recommendations.

MATERIALS AND METHODS

Relevant and unambiguous screening recommendations were extracted from applicable literature and classified into legal framework, governance, organisation, and monitoring and evaluation. The up-to-date status of screening programmes and adherence to selected recommendations was gathered from official documentation and co-authors representing cervical cancer screening programmes in all the Nordic countries.

RESULTS

A total of 168 recommendations were extracted and 54 of them were considered to be unambiguous and relevant. Forty-nine recommendations were included after synthesising similar recommendations. All Nordic countries adhere to recommendations related to legal framework, but adherence was lower with recommendations related to governance and organisation of screening. Monitoring and evaluation are also areas where adherence to recommendations could be improved.

CONCLUSIONS

The Nordic cervical cancer screening programmes have substantially decreased cancer burden despite not fully adhering to many of the recommendations. The presented gaps in adherence suggest that there is room for improvement in the screening programmes. Establishing clearer governance structures would still increase the ability to manage changes such as implementing HPV testing as the primary screening method or modifying the programme when HPV vaccinated cohorts of women enter the target age for screening.

Performance indicators in breast cancer screening in the European Union: A comparison across countries of screen positivity and detection rates

Comparable performance indicators for breast cancer screening in the European Union (EU) have not been previously reported. We estimated adjusted breast cancer screening positivity rate (PR) and detection rates (DR) to investigate variation across EU countries. For the age 50-69 years, the adjusted EU-pooled PR for initial screening was 8.9% (cross-programme variation range 3.2-19.5%) while DR of invasive cancers was 5.3/1,000 (range 3.8-7.4/1,000) and DR of ductal carcinoma in situ (DCIS) was 1.3/1,000 (range 0.7-2.7/1,000). For subsequent screening, the adjusted EU-pooled PR was 3.6% (range 1.4-8.4%), the DR was 4.0/1,000 (range 2.2-5.8/1,000) and 0.8/1,000 (range 0.5-1.3/1,000) for invasive and DCIS, respectively. Adjusted performance indicators showed remarkable heterogeneity, likely due to different background breast cancer risk and awareness between target populations, and also different screening protocols and organisation. Periodic reporting of the screening indicators permits comparison and evaluation of the screening activities between and within countries aiming to improve the quality and the outcomes of screening programmes. Cancer Screening Registries would be a milestone in this direction and EU Screening Reports provide a fundamental contribution to building them.

Key issues that need to be considered while revising the current annex of the European Council Recommendation (2003) on cancer screening

The 2003 European Council recommendation urging the Member States to introduce or scale up breast, cervical and colorectal cancer screening through an organized population-based approach has had a remarkable impact. We argue that the recommendation needs to be updated for at least two sets of reasons. First, some of the current clinical guidelines include new tests or protocols that were not available at the time of the Council document. Some have already been adopted by organized screening programs, such as newly defined age ranges for mammography screening, Human Papillomavirus (HPV)-based cervical cancer screening, fecal immunochemical test (FIT) and sigmoidoscopy for colorectal cancer screening. Second, the outcomes of randomized trials evaluating screening for lung and prostate cancer have been published recently and the balance between harms and benefits needs to be pragmatically assessed. In the European Union, research collaboration and networking to exchange and develop best practices should be regularly supported by the European Commission. Integration between primary and secondary preventive strategies through comprehensive approaches is necessary not only to maximize the reduction in cancer burden but also to control the rising trend of other noncommunicable diseases sharing the same risk factors.

Atypical glandular lesions of the cervix and risk of cervical cancer

INTRODUCTION

Cytology screening has been effective in reducing risks for cervical squamous cell carcinoma but less so for adenocarcinoma. We explored the association of atypical glandular cells or absence of glandular cells in cytology, and subsequent histological diagnoses and cancer risk.

MATERIAL AND METHODS

All women in Norway with atypical glandular cells of undetermined significance (AGUS), adenocarcinoma in situ (ACIS) and normal/benign cells, but absence of endocervical or metaplastic cells (NC-NEC) in their first cytology during 1992-2014 (NC-NEC; 2005-2014), recorded in the Cancer Registry of Norway, were included (n = 142 445). Histology diagnoses (stratified by age) within 1 and 3 years after cytology were examined. The Nelson-Aalen cumulative hazard function for gynecological cancer risk was displayed.

RESULTS

The majority of AGUS and particularly ACIS were followed with histology within 1 and 3 years. Cervical intraepithelial neoplasia (CIN) lesions were more common in women <35 than in women ≥35 years. Cervical adenocarcinoma followed 13% of ACIS after 1 and 3 years. After ACIS and AGUS, cervical adenocarcinoma was the most frequent cancer subtype. Cumulative risks of cervical adenocarcinoma following ACIS, AGUS and NC-NEC were 3.5%, 0.9% and 0.05%, respectively, after 22, 22 and 9 years of follow-up.

CONCLUSIONS

There was a high-risk of glandular malignancies after AGUS and ACIS in cytology. If effective treatment of pre-cancer and early cancer is available, cytology screening provides some level of prevention of adenocarcinoma. Lack of glandular cells did not entail a higher cancer risk.

NordScreen - an interactive tool for presenting cervical cancer screening indicators in the Nordic countries

Introduction: Quality assurance and improvement of cancer screening programs require up-to-date monitoring systems and evidence-based indicators. National quality reports exist but the definition and calculation of indicators vary making comparisons between countries difficult. The aim is to stimulate collaborative research and quality improvements in screening through freely available, comparable and regularly updated quality indicators. The project currently includes data on cervical cancer screening but population-based screening programs for breast cancer and colorectal cancer may be included in the future. Material and methods: Through a network of Nordic and Baltic screening managers, population-based individual screening data from each country were converted to standard format in each collaborative center, aggregated by the same R program script and then uploaded to the NordScreen online platform. Registry data included all cervical tests except for Finland where only tests based on invitation are included. Results: The NordScreen collaboration has so far collated standardized indicators based on 32.8 million screening tests from four Nordic countries and Estonia. Interactive comparison of test coverage and distribution of women by number of tests are currently possible online. In 2016, the test coverage within a time interval of 5.5 years in the age group 30-64 year-olds was between 78 and 84% in Iceland, Norway and Sweden whereas 70% in Finland. The application allows users to choose indicator specifications interactively. Conclusions: NordScreen is a pilot model for comparable, reliable and accessible cross-country comparisons of cancer screening. Comparability between countries is enhanced by a uniform data structure and standardized calculations. The comparison of coverage rates to national figures shows that the methods used nationally and in the NordScreen project produce similar results.

Performance of colorectal cancer screening in the European Union Member States: data from the second European screening report

OBJECTIVE

To present comparative data about the performance of colorectal cancer (CRC) screening programmes in the European Union Member States (EU MSs).

DESIGN

Cross-sectional study. We analysed key performance indicators-participation rate, positivity rate (PR), detection rate (DR) and positive predictive value for adenomas and CRC-based on the aggregated quantitative data collected for the second EU screening report. We derived crude and pooled (through a random effects model) estimates to describe and compare trends across different MSs/regions and screening protocols.

RESULTS

Participation rate was higher in countries adopting faecal immunochemical test (FIT) (range: 22.8%-71.3%) than in those using guaiac faecal occult blood test (gFOBT) (range 4.5%-66.6%), and it showed a positive correlation (ρ=0.842, p<0.001) with participation in breast cancer screening in the same areas. Screening performance showed a large variability. Compliance with referral for colonoscopy (total colonoscopy (TC)) assessment ranged between 64% and 92%; TC completion rate ranged between 92% and 99%. PR and DR of advanced adenomas and CRC were higher in FIT, as compared with gFOBT programmes, and independent of the protocol among men, older subjects and those performing their first screening.

CONCLUSIONS

The variability in the results of quality indicators across population-based screening programmes highlights the importance of continuous monitoring, as well as the need to promote quality improvement efforts, as recommended in the EU guidelines. The implementation of monitoring systems, ensuring availability of data for the entire process, together with initiatives aimed to enhance reproducibility of histology and quality of endoscopy, represent a priority in screening programmes management.

Invitation strategies and coverage in the population-based cancer screening programmes in the European Union

The aim of this study was to describe the compliance of the population-based cancer screening programmes in the European Union Member States to the invitation strategies enumerated in the European Guidelines and the impact of such strategies on the invitational coverage. Experts in screening programme monitoring from the respective countries provided data. Coverage by invitation was calculated as the proportion of individuals in the target age range receiving a screening invitation over the total number of annualized eligible population. The invitation strategies of 30 breasts, 25 cervical and 27 colorectal national or regional population-based screening programmes are described. Individual mail invitations are sent by 28 breasts, 20 cervical and 25 colorectal screening programmes. Faecal occult blood test kits are sent by post in 17 of the colorectal cancer screening programmes. The majority of programmes claimed to have a population registry, although some use health insurance data as the database for sending invitations. At least 95% invitation coverage was reached by 16 breast, six cervical and five colorectal screening programmes. Majority of the programmes comply with the invitation strategies enumerated in the European guidelines, although there is still scope for improvements. Coverage by invitation is below the desirable level in many population-based cancer screening programmes in European Union.

Status of implementation and organization of cancer screening in The European Union Member States-Summary results from the second European screening report

The second report on the implementation status of cancer screening in European Union (EU) was published in 2017. The report described the implementation status, protocols and organization (updated till 2016) and invitation coverage (for index year 2013) of breast, cervical and colorectal cancer screening in the EU. Experts in screening programme monitoring (N = 80) from the EU Member States having access to requisite information in their respective countries provided data on breast, cervical and colorectal cancer screening through online questionnaires. Data was collected for screening performed in the framework of publicly mandated programmes only. Filled in questionnaires were received from 26 Member States for all three sites and from one Member State for breast cancer only. Substantial improvement in screening implementation using population-based approach was documented. Among the age-eligible women, 94.7% were residents of Member States implementing or planning population-based breast cancer screening in 2016, compared to 91.6% in 2007. The corresponding figures for cervical cancer screening were 72.3 and 51.3% in 2016 and 2007, respectively. Most significant improvement was documented for colorectal cancer screening with roll-out ongoing or completed in 17 Member States in 2016, compared to only five in 2007. So the access to population-based screening increased to 72.4% of the age-eligible populations in 2016 as opposed to only 42.6% in 2007. The invitation coverage was highly variable, ranging from 0.2-111% for breast cancer, 7.6-105% for cervical cancer and 1.8-127% for colorectal cancer in the target populations. In spite of the considerable progress, much work remains to be done to achieve optimal effectiveness. Continued monitoring, regular feedbacks and periodic reporting are needed to ensure the desired impacts of the programmes.

HPV genotype profile in a Norwegian cohort with ASC-US and LSIL cytology with three year cumulative risk of high grade cervical neoplasia

OBJECTIVE

To explore the HPVgenotype profile in Norwegian women with ASC-US/LSIL cytology and the subsequent risk of high-grade cervical neoplasia (CIN 3+).

METHODS

In this observational study delayed triage of ASC-US/LSIL of 6058 women were included from 2005 to 2010. High-risk HPV detection with Hybrid Capture 2 (HC2) was used and the HC2+ cases were genotyped with in-house nmPCR. Women were followed-up for histologically confirmed CIN3+ within three years of index HPV test by linkage to the screening databases at the Cancer Registry of Norway.

RESULTS

HC2 was positive in 45% (2756/6058) of the women. Within 3years CIN3+ was diagnosed in 26% of women<34year and in 15%≥34year. HC2 was positive at index in 94% of CIN3+ cases and negative in 64 cases including three women with cervical carcinomas. Women<34years with single infections of HPV 16, 35, 58 or 33 or multiple infections including HPV 16, 52, 33 or 31 were associated with highest proportions of CIN 3+. Older women with single infection with HPV 16, 33, 31 or 35 or multiple infections including HPV 16, 33, 31 or 18/39 were more likely to develop CIN 3+.

CONCLUSIONS

HPV 16 and HPV 33 at baseline both as single or multiple infections, were associated with the highest risk for CIN3+. Among older women, all 13 high-risk genotypes as single infection were associated with >20% risk of CIN3+. Further studies are necessary to risk stratify the individual genotypes to reduce the number of colposcopies in Norway.

Adverse Pregnancy Outcomes After Treatment for Cervical Intraepithelial Neoplasia

OBJECTIVE

To explore associations between specific treatments for intraepithelial or early invasive cervical lesions and adverse pregnancy outcomes.

METHODS

We conducted a population-based cohort study in which treatment data from the Cancer Registry of Norway were linked to the Medical Birth Registry of Norway to identify adverse pregnancy outcomes. All women (n=545,243) with singleton births (N=943,321) in Norway during 1998-2014 were included; 9,554 of births were in women treated before delivery. Hazard ratios (HRs) with 95% confidence intervals (CIs) were derived from Cox regression models.

RESULTS

There was a significant association between preterm birth and previous treatment of cervical lesions overall (9.7 compared with 5.3%; HR 1.8, 95% CI 1.7-2.0). The strongest associations were seen for cold knife (13 compared with 5.3%; HR 2.6, 95% CI 1.3-5.3) and laser conization (12 compared with 5.3%; HR 2.3, 95% CI 2.0-2.5). The association was stronger for preterm birth at earlier gestational ages and increased with amount of tissue excised. Furthermore, the association weakened with calendar year of treatment. There was also an association with increased risks of spontaneous abortion (0.5 compared with 0.2%; HR 2.5, 95% CI 1.7-3.7), and the strongest associations were seen for laser conization (0.6 compared with 0.2%; HR 3.0, 95% CI 1.8-5.3) and a loop electrosurgical excision procedure (LEEP) (0.4 compared with 0.2%; HR 2.3, 95% CI 1.3-4.0).

CONCLUSION

Treatment with major excisional procedures, including LEEP, was associated with increased risks of preterm birth and spontaneous abortion. The risk of preterm birth was highest at early gestational ages and for those with the largest amount of tissue excised. Women should be informed about their future risk of adverse pregnancy outcomes, particularly preterm birth, after excisional treatment for cervical lesions.

Cervical cancer incidence in elderly women-biology or screening history?

AIM

In many countries, the age-specific pattern of cervical cancer incidence is currently bipolar with peaks at for instance 45 and 65 years of age. Consequently, a large proportion of cervical cancer cases are presently diagnosed in women above the screening age. The purpose of the study was to determine whether this bipolar pattern in age-specific incidence of cervical cancer reflects underlying biology or can be explained by the fact that the data come from birth cohorts with different screening histories.

METHODS

Combination of historical data on cervical screening and population-based cancer incidence data from Denmark 1943-2013, Finland and Norway 1953-2013, and Sweden 1958-2013.

RESULTS

Since the implementation of screening, the incidence of cervical cancer has decreased for each successive birth cohort. All birth cohorts showed a unipolar age-specific pattern. In unscreened women in Denmark and Sweden, the incidence peaked around the age of 50; the peak was less marked in Finland; while peak age for unscreened women could not be determined for Norway due to widespread opportunistic screening. The current old-age peak in the incidence of cervical cancer represents residuals from unscreened or underscreened birth cohorts.

CONCLUSION

The current bipolar pattern in age-specific incidence of cervical cancer can largely be explained by the different screening histories of successive birth cohorts. While it is reasonable to offer screening to elderly women today, birth cohort trends in disease burden should be carefully monitored to justify permanent changes in upper screening age.

Personal and provider level factors influence participation to cervical cancer screening: A retrospective register-based study of 1.3 million women in Norway

High coverage is essential for an effective screening programme. Here we present screening barriers and facilitators among 1.3 million women aged 25-69years eligible for screening within the Norwegian Cervical Cancer Screening Program (NCCSP). We defined non-adherence as no screening test in 2008-2012. We divided adherent women into those screened spontaneously, and those who had a smear after receiving a reminder from the NCCSP. Explanatory variables were extracted from several nationwide registers, and modelled by modified Poisson regression. In total, 34% of women were non-adherent. 31% of native Norwegians were non-adherent, compared to 50% of immigrants. Immigrant status was a strong predictor of non-adherence, but the vast majority of non-adherent women were still native Norwegians. Higher non-adherence rates were associated with having a male general practitioner (GP), a foreign GP, a young GP, and distance to the screening site. Being unmarried, having no children, having lower socioeconomic position and region of residence predicted non-adherence and, to a smaller extent, reminded adherence to screening. In contrast, previous experience with cervical abnormalities substantially increased adherence to screening. The population-based screening programme promotes equity by recruiting women who are less likely to participate spontaneously. However, socioeconomic disparities were evident in a country with a nationwide programme and a policy of equal access to health care. Initiatives aimed at removing practical and financial barriers to equitable screening delivery and at reducing the effect of sociodemographic attributes on screening participation are needed.

Quality assurance of human papillomavirus (HPV) testing in the implementation of HPV primary screening in Norway: an inter-laboratory reproducibility study

Background

Human papillomavirus (HPV) testing as primary screening for cervical cancer is currently being implemented in Norway in a randomized controlled fashion, involving three laboratories. As part of the quality assurance programme of the implementation, an evaluation of the inter-laboratory reproducibility of the HPV test was initiated, to ensure satisfactory HPV test reliability in all three laboratories.

Methods

The HPV test used is the cobas 4800 HPV Test, detecting 14 high-risk types with individual HPV genotype results for HPV16 and HPV18. In addition to the three laboratories involved in the implementation, the Norwegian HPV reference laboratory was included as a fourth comparative laboratory. A stratified sample of 500 cervical liquid based cytology (LBC) samples was used in the evaluation, with an aim towards a high-risk HPV positivity of ~25%. Samples were collected at one laboratory, anonymized, aliquoted, and distributed to the other laboratories.

Results

Comparison of the test results of all four laboratories revealed a 95.6% agreement, an 86.3% positive agreement and a kappa value of 0.94 (95% CI 0.92–0.97). For negative cytology specimens, there was a 95.8% overall agreement, a 67.4% positive agreement, and a kappa value of 0.88 (95% CI 0.80–0.93). For abnormal cytology specimens, there was a 95.8% overall agreement, a 95.5% positive agreement, and a kappa value of 0.86 (95% CI 0.71–0.97).

Conclusions

The study showed a high inter-laboratory reproducibility of HPV testing, implying satisfactory user performance and reliability in the laboratories involved in the implementation project. This is important knowledge and we recommend similar studies always to be performed prior to the introduction of new screening routines.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-2028-7) contains supplementary material, which is available to authorized users.

Impact of scheduled appointments on cervical screening participation in Norway: a randomised intervention

BACKGROUND

The main barrier to optimal effect in many established population-based screening programmes against cervical cancer is low participation. In Norway, a routine health service integrated population-based screening programme has been running since 1995, using open invitations and reminders. The aim of this randomised health service study was to pilot scheduled appointments and assess their potential for increased participation.

METHODS

Within the national screening programme, we randomised 1087 women overdue for screening to receive invitations with scheduled appointments (intervention) or the standard open reminders (control). Letters were sent 2-4 weeks before the scheduled appointments at three centres: a midwife clinic, a public healthcare centre and a general practitioner centre. The primary outcome was participation at 6 months of follow-up. Secondary outcomes were participation at 1 and 3 months. Risk ratios (RRs) overall, and stratified by screening centre, age group and previous participation, were calculated using log-binomial regression.

RESULTS

At 6 months, 20% of the 510 women in the control group and 37% of the 526 women in the intervention group had participated in screening, excluding 51 women in total from analysis due to participation just before invitation and therefore not yet visible in the central records. The RR for participation at 6 months was 1.9 (95% CI 1.5 to 2.3). There was no significant heterogeneity between centres or age groups. Participation increased among women both with (RR 1.7; 95% CI 1.4 to 2.1) and without (RR 3.5; 95% CI 1.3 to 9.2) previous participation. The RRs for participation at 1 and 3 months were 4.0 (95% CI 2.6 to 6.2) and 2.7 (95% CI 2.1 to 3.5), respectively.

CONCLUSIONS

Scheduled appointments increased screening participation consistently across all target ages and screening centres among women overdue for screening. Participation increased also among women with no previous records of cervical screening.

Using Decision-Analytic Modeling to Isolate Interventions That Are Feasible, Efficient and Optimal: An Application from the Norwegian Cervical Cancer Screening Program

BACKGROUND

Decision makers often need to simultaneously consider multiple criteria or outcomes when deciding whether to adopt new health interventions.

OBJECTIVES

Using decision analysis within the context of cervical cancer screening in Norway, we aimed to aid decision makers in identifying a subset of relevant strategies that are simultaneously efficient, feasible, and optimal.

METHODS

We developed an age-stratified probabilistic decision tree model following a cohort of women attending primary screening through one screening round. We enumerated detected precancers (i.e., cervical intraepithelial neoplasia of grade 2 or more severe (CIN2+)), colposcopies performed, and monetary costs associated with 10 alternative triage algorithms for women with abnormal cytology results. As efficiency metrics, we calculated incremental cost-effectiveness, and harm-benefit, ratios, defined as the additional costs, or the additional number of colposcopies, per additional CIN2+ detected. We estimated capacity requirements and uncertainty surrounding which strategy is optimal according to the decision rule, involving willingness to pay (monetary or resources consumed per added benefit).

RESULTS

For ages 25 to 33 years, we eliminated four strategies that did not fall on either efficiency frontier, while one strategy was efficient with respect to both efficiency metrics. Compared with current practice in Norway, two strategies detected more precancers at lower monetary costs, but some required more colposcopies. Similar results were found for women aged 34 to 69 years.

CONCLUSIONS

Improving the effectiveness and efficiency of cervical cancer screening may necessitate additional resources. Although efficient and feasible, both society and individuals must specify their willingness to accept the additional resources and perceived harms required to increase effectiveness before a strategy can be considered optimal.

Towards better implementation of cancer screening in Europe through improved monitoring and evaluation and greater engagement of cancer registries

Proposals to improve implementation, monitoring and evaluation of breast, cervical and colorectal cancer screening programmes have been developed in a European project involving scientists and professionals experienced in cancer registration (EUROCOURSE). They call for a clear and more active role for cancer registries through better interfaces with cancer screening programmes and adapting data contents of cancer registries for evaluation purposes. Cancer registries are recognised as essential for adequate evaluation of cancer screening programmes, but they are not involved in screening evaluation in several European countries. This is a key barrier to improving the effectiveness of programmes across Europe. The variation in Europe in the implementation of cancer screening offers a unique opportunity to learn from best practices in collaboration between cancer registries and screening programmes. Population-based cancer registries have experience and tools in collecting and analysing relevant data, e.g. for diagnostic and therapeutic determinants of mortality. In order to accelerate improvements in cancer control we argue that cancer registries should take co-responsibility in promoting effective screening evaluation in Europe. Additional investments are vital to further development of infrastructures and activities for screening evaluation and monitoring in the national settings and also at the pan-European level. The EUROCOURSE project also aimed to harmonise implementation of the European quality assurance guidelines for cancer screening programmes across Europe through standardising routine data collection and analysis, and definitions for key performance indicators for screening registers. Data linkage between cancer and screening registers and other repositories of demographic data and cause of death and where available clinical registers is key to implementing the European screening standards and thereby reducing the burden of disease through early detection. Greater engagement of cancer registries in this collaborative effort is also essential to develop adequate evaluation of innovations in cancer prevention and care.

50 years of screening in the Nordic countries: quantifying the effects on cervical cancer incidence

BACKGROUND

Nordic countries' data offer a unique possibility to evaluate the long-term benefit of cervical cancer screening in a context of increasing risk of human papillomavirus infection.

METHODS

Ad hoc-refined age-period-cohort models were applied to the last 50-year incidence data from Denmark, Finland, Norway and Sweden to project expected cervical cancer cases in a no-screening scenario.

RESULTS

In the absence of screening, projected incidence rates for 2006-2010 in Nordic countries would have been between 3 and 5 times higher than observed rates. Over 60,000 cases or between 41 and 49% of the expected cases of cervical cancer may have been prevented by the introduction of screening in the late 1960s and early 1970s.

CONCLUSIONS

Our study suggests that screening programmes might have prevented a HPV-driven epidemic of cervical cancer in Nordic countries. According to extrapolations from cohort effects, cervical cancer incidence rates in the Nordic countries would have been otherwise comparable to the highest incidence rates currently detected in low-income countries.

Detection rates of precancerous and cancerous cervical lesions within one screening round of primary human papillomavirus DNA testing: prospective randomised trial in Finland

OBJECTIVE

To compare the detection rates of precancerous and cancerous cervical lesions by human papillomavirus (HPV) DNA testing and by conventional cytology screening.

DESIGN

Prospective randomised trial. Two cohorts were followed over one screening round of five years, screened initially by primary HPV DNA testing or by primary Pap test.

SETTING

Population based programme for cervical cancer screening in Finland.

PARTICIPANTS

Women aged 25-65 years invited for screening in 2003-07 (101,678 in HPV arm; 101,747 in conventional cytology arm).

INTERVENTION

Women were randomly allocated (1:1) to primary HPV DNA screening followed by cytology triage if they had positive results, or to primary cytology screening. Screening method was disclosed at the screening visit. Trial personnel involved were aware of all test results.

MAIN OUTCOME MEASURES

Cumulative detection rates of cervical intraepithelial neoplasia (CIN), adenocarcinoma in situ (AIS), and invasive cervical cancer before the second screening (after five years) or before 31 December 2008. Lesions detected at screening and during the five year interval were included.

RESULTS

1010 and 701 precancerous or cancerous lesions were detected during an average follow-up of 3.6 years in the HPV and cytology arms, respectively. Among invited women, the hazard ratio was 1.53 (95% confidence interval l.28 to 1.84) for CIN grade 1, 1.54 (1.33 to 1.78) for CIN 2, 1.32 (1.09 to 1.59) for CIN 3 or AIS, and 0.81 (0.48 to 1.37) for cervical cancer. In 25-34 year old participants, the cumulative hazard (or cumulative detection rate) was 0.0057 (0.0045 to 0.0072) for HPV screening versus 0.0046 (0.0035 to 0.0059) for conventional screening; corresponding data for women aged 35 years and older were 0.0022 (0.0019 to 0.0026) and 0.0017 (0.0014 to 0.0021), respectively.

CONCLUSIONS

Primary HPV DNA screening detects more cervical lesions than primary cytology within one screening round of five years. Even if the detection rate of CIN 3 or AIS increased in the HPV arm in both age groups, the absolute difference in cumulative rates in women aged 35 years or older was small. By carefully selecting age groups and screening intervals, HPV screening could increase the overall detection rate of cervical precancerous lesions only slightly. However, these findings should be interpreted in the context of the high level of opportunistic screening that occurs in Finland.

TRIAL REGISTRATION

International Standard Randomised Controlled Trial ISRCTN23885553.

Mortality audit of the Finnish cervical cancer screening program

Incidence-based evaluations of cervical cancer screening programs have suggested age-specific impacts and there is uncertainty regarding the effectiveness of screening outside the ages of 30-60 years. We audited the screening histories of cervical cancer deaths and conducted a case-control evaluation of the effectiveness of organized screening in different ages with mortality as outcome. We included all 506 cervical cancer deaths in Finland in 2000-2009 due to cancers diagnosed in 1990 or later, and 3,036 controls matched by age at diagnosis to the cases. Squamous cell carcinoma constituted 59% of the cases, adenocarcinomas 29%, and the remaining 12% were other specified and unspecified cervical malignancies. Most deaths (54%) were due to cancers diagnosed more than 5 years after last screening invitation, 24% were diagnosed among nonattenders and only 14% of deaths occurred among women who had attended invitational screening. The risk reduction associated with attending a single program screen at an age below 40 was nonsignificant (OR 0.70; 95% CI 0.33-1.48), while clear risk reductions were observed after screening at the age of 40-54 (OR 0.33; CI 0.20-0.56) and 55-69 (OR 0.29; CI 0.16-0.54). This study also provides some indication of a long-lasting additional effect of screening at the age of 65. Possible avenues for improving the effectiveness of the Finnish screening program include efforts to increase attendance and an extension of the target ages to include 65-to 69-year-old women. The potential benefit of increasing the sensitivity of the screening test or shortening the screening interval is smaller.

Validation of histological diagnoses in a national cervical screening register

BACKGROUND

Monitoring and evaluation of cancer screening programmes require accurate data on invitations, visits, test results, diagnoses and management. The purpose of this study was to evaluate the completeness and accuracy of histological diagnoses (cervical precancerous lesions and cancer) in the Finnish cervical cancer screening register by comparing data with the cancer register and the administrative hospital discharge register.

MATERIAL AND METHODS

Screening data covering all 16 353 screening episodes that resulted in a referral for colposcopy over the period of 1998-2007 were individually linked with hospital discharge and cancer register data using the unique personal identifier. Agreement between registers, as well as sensitivity, coverage and positive predictive values (PPV) for the screening register and the hospital discharge register diagnosis, were estimated. Invasive cases in the cancer register and pooled cases of precancerous lesions were used as reference case populations.

RESULTS

The sensitivity of the screening register for cervical cancer was 69%, the coverage 100% and the PPV 77%. Corresponding values for the hospital discharge register were 81%, 100% and 83%, respectively. Sensitivity of the screening register for cervical intraepithelial neoplasia grade 2 or worse (CIN2+) against the pooled case population was 89% and coverage 99%. Corresponding values for the hospital discharge register were 78% and 93%. Kappa-values for pair-wise agreement between the three registers ranged between 0.73 and 0.79, often the lesion grade was lower in the screening register than in the other two registers.

CONCLUSIONS

The data in the screening register has high coverage and is thus useful for statistical and evaluation purposes. However, in order to improve the accuracy of diagnostic information, there are grounds to consider data retrieval through systematic linkage to other health care registers.

Supersensitive time-resolved immunofluorometric assay of free prostate-specific antigen with nanoparticle label technology

BACKGROUND

The extreme specific activity of the long-lifetime fluorescent europium(III) chelate nanoparticles and the enhanced monovalent binding affinity of multivalent nanoparticle-antibody bioconjugates are attractive for noncompetitive immunoassay.

METHODS

We used a noncompetitive, two-step immunoassay design to measure free prostate-specific antigen (PSA). Europium(III) chelate nanoparticles (107 nm in diameter) were coated with a monoclonal anti-PSA antibody (intrinsic affinity, 6 x 10(9) L/mol). The nanoparticle-antibody bioconjugates had an average of 214 active binding sites per particle and a monovalent binding affinity of 7 x 10(10) L/mol. The assay was performed in a low-fluorescence microtitration well passively coated with an another monoclonal anti-PSA antibody (affinity, 2 x 10(10) L/mol), and the europium(III) fluorescence was measured directly from the bottom of the well by a standard time-resolved microtitration plate fluorometer.

RESULTS

The detection limit (mean + 2 SD) was 0.040 ng/L (7.3 x 10(5) molecules/mL), and the dynamic detection range covered four orders of magnitude in a 3-h total assay time. The imprecision (CV) over the whole assay range was 2-10%. The detection limit of the assay was limited by the fractional nonspecific binding of the bioconjugate to the solid phase (0.05%), which was higher than the nonspecific binding of the original antibody (<0.01%).

CONCLUSIONS

The sensitivity of the new assay is equal to that of the ambient-analyte, microspot immunoassay and will be improved by use of optimized, high binding-site density nanoparticle-antibody bioconjugates with reduced nonspecific binding and improved monovalent binding affinity.

Zeptomole detection sensitivity of prostate-specific antigen in a rapid microtitre plate assay using time-resolved fluorescence

Prostate-specific antigen (PSA) was detected in microtitre wells coated with a PSA-specific antibody using biotinylated antibody and streptavidin-coated, highly fluorescent 107 nm nanoparticles, which contained more than 30000 europium ions entrapped by beta-diketones. PSA was monitored directly on the surface of a well without any additional enhancement step. The sensitivity of the assay was 1.6 ng/L, corresponding to 50 fmol/L or 250 zeptomoles (250 x 10(-21) mol/L) of PSA. The high specific activity and low non-specific binding of the streptavidin-coated nanoparticles improved the sensitivity of the PSA assay 100-fold compared to the conventional europium-labelled streptavidin tracer in the same assay format. Additionally, the streptavidin-coated nanoparticle label made very rapid assays possible, due to the high affinity of the streptavidin-biotin complex and a high number of binding sites available for tracing the biotinylated antibody on the surface. Due to the inherent problems of tracing analyte with a complex of biotinylated antibody and streptavidin-coated nanoparticles, the streptavidin-coated nanoparticles reacting with the surface-captured analyte and biotinylated antibody was favoured and factors influencing this are discussed. This universal labelling technology can be applied to detect any biotinylated molecule, either in solution or on a solid phase, in order to improve detection sensitivities in many areas of biochemical analysis, such as cyto- and histochemistry, multianalyte DNA-chip assays and single-particle assays.

A group-specific microbiological test for the detection of tetracycline residues in raw milk

The potentiality of using a luminescent Escherichia coli strain for the specific detection of tetracycline residues in raw bovine milk was investigated. The sensor cells contain a reporter plasmid carrying the bacterial luciferase operon of Photorhabdus luminescens under the control of the tetracycline responsive control region from transposon Tn10. Incubation of the cells with the sample containing tetracyclines increases the light emission of the sensor cells. The most sensitive tetracycline detection was achieved in 120 min and by using CDTA as a chelating agent in the assay. Heat-treatment of milk before the assay decreased the variations in background luminescence signals and in tetracycline-induced luminescence between different milk samples. The detection limits for tetracycline, oxytetracycline, chlortetracycline, doxycycline, methacycline, demeclocycline, and minocycline were between 2 and 35 ng/mL. Nontetracycline antibiotics did not significantly interfere with the detection of tetracyclines.

Qualitative detection of tetracycline residues in milk with a luminescence-based microbial method: the effect of milk composition and assay performance in relation to an immunoassay and a microbial inhibition assay

Performance of Tet-Lux, a newly developed microbiological test for the detection of tetracycline residues in raw milk, based on tetracycline-controlled luminescence activation of the test bacteria, was evaluated in bovine milks with variable amounts of somatic cells, bacteria, fat, protein, and natural inhibitory compounds. The sensitivity of Tet-Lux was also compared to a commercially available tetracycline immunoassay (Snap, Idexx Laboratories Inc.) and to a microbial inhibition test (Delvotest SP, Gist-Brogades). There were slight differences in the luminescence signals between different milk samples, but no single factor could be pointed out to be responsible for them. There appeared to be a modest inverse relationship between luminescence and increasing fat and protein content. The amount of somatic cells, bacteria, and the natural inhibitors lysozyme and lactoferrin did not affect the luminescence response. The test fulfilled the sensitivity requirement specified by the European Union (maximum residue limit 100 ng/ml for tetracyclines). The Tet-Lux test was clearly more sensitive to all tetracyclines tested (oxytetracycline, tetracycline, chlortetracycline, doxycycline, demeclocycline, methacycline, minocycline) than Delvotest SP, and for five tetracyclines out of seven more sensitive than Snap. The test provides a fast, simple, and robust microbial method for the qualitative detection of tetracycline residues in milk.